1. Field of the Invention
The present invention relates to a multi-scale indicator and, more particularly, to an improved indicator which includes both a main scale and a sub-scale such as those used in fuel oil meters for automobiles, or the like, which give a subsidiary indication in addition to an ordinary measurement indication.
2. Description of the Prior Art
In recent years, the objects of indicators have diversified with the advance of improvements of functions in automobiles, airplanes and the other machine equipment. As a result, a multi-scale indicator which has a mechanism capable of giving different level indications has generally been utilized.
For example, as shown in FIGS. 1 and 2, there is provided a multi-scale indicator generally employed as a fuel oil meter for use in automobile or the like which comprises a scale disc 1 provided with a main scale 2 and a sub-scale 3 therein. On the top of the scale disc 1, a pointer 4 is provided, while on the back side of the scale disc 1, a main scale prism 5, which is formed as a circular disc shape having a diameter substantially the same as that of the scale disc 1 is disposed. The main scale prism 5 has a recess, and a light source 6 is disposed in the recess. As a light emmanating from the light source 6 can be passed through the main scale prism 5 and is diffusely reflected therein, each scale may thus be brightly illuminated.
The indicator having such a construction described above is operated as follows. The pointer 4 usually indicates the main scale 2. However, the pointer 4 indicates the sub-scale 3 displaying an enlarged value by switchover of the range of the indicator when the pointer 4 is moved to the predetermined warning zone R located in proximity to the end of the main scale 2. Simultaneously with the switchover of the range, a warning lamp A which is located in a lower left portion of the scale disc 1 is lit, clearly showing that the pointer 4 indicates the sub-scale 3.
Specifically, when the pointer 4 is moved to the red-zone R of main scale 2 which indicates that fuel oil will be soon exhausted, an automatic change-over switch (not shown) which is contained in an electrical circuit means of the indicator is operated, and point 4 thus indicates the sub-scale 3 by switchover of the range simultaneously with lighting of the warning lamp A.
However, the driver discriminates visually whether the pointer 4 indicates the main scale 2 or the sub-scale 3 only by observation of the ON-OFF operation of the warning lamp A. Therefore, when the warning lamp A is turned off, the driver sees both the main scale 2 and the sub-scale 3 displayed in the indicator simultaneously. As a result, in the conventional indicator, even if when the warning lamp A is lit, the driver is likely to make a misreading as to whether the pointer 4 indicates the main scale 2 or the sub-scale 3. Further, similar situations have occurred due to the drivers failure to notice that the warning lamp A is lit.